Home Home > GIT Browse
summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJustin Maggard <jmaggard10@gmail.com>2016-02-09 15:52:08 -0800
committerSasha Levin <sasha.levin@oracle.com>2016-03-09 13:15:16 -0500
commit94a7d752e43717119822fee8b04be903e694017e (patch)
treebaf69c137418bad87707fcd5448a49c72badc0ef
parentfb5b8ac0043cc2c0e8816341f8a875ab320563fe (diff)
cifs: fix out-of-bounds access in lease parsing
[ Upstream commit deb7deff2f00bdbbcb3d560dad2a89ef37df837d ] When opening a file, SMB2_open() attempts to parse the lease state from the SMB2 CREATE Response. However, the parsing code was not careful to ensure that the create contexts are not empty or invalid, which can lead to out- of-bounds memory access. This can be seen easily by trying to read a file from a OSX 10.11 SMB3 server. Here is sample crash output: BUG: unable to handle kernel paging request at ffff8800a1a77cc6 IP: [<ffffffff8828a734>] SMB2_open+0x804/0x960 PGD 8f77067 PUD 0 Oops: 0000 [#1] SMP Modules linked in: CPU: 3 PID: 2876 Comm: cp Not tainted 4.5.0-rc3.x86_64.1+ #14 Hardware name: NETGEAR ReadyNAS 314 /ReadyNAS 314 , BIOS 4.6.5 10/11/2012 task: ffff880073cdc080 ti: ffff88005b31c000 task.ti: ffff88005b31c000 RIP: 0010:[<ffffffff8828a734>] [<ffffffff8828a734>] SMB2_open+0x804/0x960 RSP: 0018:ffff88005b31fa08 EFLAGS: 00010282 RAX: 0000000000000015 RBX: 0000000000000000 RCX: 0000000000000006 RDX: 0000000000000000 RSI: 0000000000000246 RDI: ffff88007eb8c8b0 RBP: ffff88005b31fad8 R08: 666666203d206363 R09: 6131613030383866 R10: 3030383866666666 R11: 00000000000002b0 R12: ffff8800660fd800 R13: ffff8800a1a77cc2 R14: 00000000424d53fe R15: ffff88005f5a28c0 FS: 00007f7c8a2897c0(0000) GS:ffff88007eb80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: ffff8800a1a77cc6 CR3: 000000005b281000 CR4: 00000000000006e0 Stack: ffff88005b31fa70 ffffffff88278789 00000000000001d3 ffff88005f5a2a80 ffffffff00000003 ffff88005d029d00 ffff88006fde05a0 0000000000000000 ffff88005b31fc78 ffff88006fde0780 ffff88005b31fb2f 0000000100000fe0 Call Trace: [<ffffffff88278789>] ? cifsConvertToUTF16+0x159/0x2d0 [<ffffffff8828cf68>] smb2_open_file+0x98/0x210 [<ffffffff8811e80c>] ? __kmalloc+0x1c/0xe0 [<ffffffff882685f4>] cifs_open+0x2a4/0x720 [<ffffffff88122cef>] do_dentry_open+0x1ff/0x310 [<ffffffff88268350>] ? cifsFileInfo_get+0x30/0x30 [<ffffffff88123d92>] vfs_open+0x52/0x60 [<ffffffff88131dd0>] path_openat+0x170/0xf70 [<ffffffff88097d48>] ? remove_wait_queue+0x48/0x50 [<ffffffff88133a29>] do_filp_open+0x79/0xd0 [<ffffffff8813f2ca>] ? __alloc_fd+0x3a/0x170 [<ffffffff881240c4>] do_sys_open+0x114/0x1e0 [<ffffffff881241a9>] SyS_open+0x19/0x20 [<ffffffff8896e257>] entry_SYSCALL_64_fastpath+0x12/0x6a Code: 4d 8d 6c 07 04 31 c0 4c 89 ee e8 47 6f e5 ff 31 c9 41 89 ce 44 89 f1 48 c7 c7 28 b1 bd 88 31 c0 49 01 cd 4c 89 ee e8 2b 6f e5 ff <45> 0f b7 75 04 48 c7 c7 31 b1 bd 88 31 c0 4d 01 ee 4c 89 f6 e8 RIP [<ffffffff8828a734>] SMB2_open+0x804/0x960 RSP <ffff88005b31fa08> CR2: ffff8800a1a77cc6 ---[ end trace d9f69ba64feee469 ]--- Signed-off-by: Justin Maggard <jmaggard@netgear.com> Signed-off-by: Steve French <smfrench@gmail.com> CC: Stable <stable@vger.kernel.org> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--fs/cifs/smb2pdu.c24
1 files changed, 14 insertions, 10 deletions
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 894f259d3989..657a9c5c4fff 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -1042,21 +1042,25 @@ parse_lease_state(struct TCP_Server_Info *server, struct smb2_create_rsp *rsp,
{
char *data_offset;
struct create_context *cc;
- unsigned int next = 0;
+ unsigned int next;
+ unsigned int remaining;
char *name;
data_offset = (char *)rsp + 4 + le32_to_cpu(rsp->CreateContextsOffset);
+ remaining = le32_to_cpu(rsp->CreateContextsLength);
cc = (struct create_context *)data_offset;
- do {
- cc = (struct create_context *)((char *)cc + next);
+ while (remaining >= sizeof(struct create_context)) {
name = le16_to_cpu(cc->NameOffset) + (char *)cc;
- if (le16_to_cpu(cc->NameLength) != 4 ||
- strncmp(name, "RqLs", 4)) {
- next = le32_to_cpu(cc->Next);
- continue;
- }
- return server->ops->parse_lease_buf(cc, epoch);
- } while (next != 0);
+ if (le16_to_cpu(cc->NameLength) == 4 &&
+ strncmp(name, "RqLs", 4) == 0)
+ return server->ops->parse_lease_buf(cc, epoch);
+
+ next = le32_to_cpu(cc->Next);
+ if (!next)
+ break;
+ remaining -= next;
+ cc = (struct create_context *)((char *)cc + next);
+ }
return 0;
}